The research proposed in this grant will be directed toward understanding the role of one of the subunits, the alpha-subunit, which composes the multi-enzyme complex, tryptophan synthetase (bacterial). Utilizing both chemically and mutationally altered alpha-subunits, structure-function relationships which are concerned with the catalytic activity of the protein alone and in combination with the other subunit, the Beta 2-subunit, will be explored. Additional information regarding the specific protein-protein interactions involved in the formation of the active, fully constituted multi-enzyme complex will be sought. BIBLIOGRAPHIC REFERENCES: H. G. Hodo, J. Murphy, J. K. Hardman and R. Myers. Substrate Interactions with the alpha-Subunit of the Escherichia coli Tryptophan Synthase: A Kinetic Study of the Wild-Type alpha-Subunit. Arch. Biochem. Biophys. 181 (May) 1977. C. L. Patterson, H. G. Hodo and J. K. Hardman. Substrate Interaction with the alpha-Subunit of the Escherichia coli Tryptophan Synthase: A Study of the Activity of Mutant alpha-Subunits. Arch. Biochem. Biophys. 181 (May) 1977.